Fig. 3From: Heart rate and heart rate variability comparison between postural orthostatic tachycardia syndrome versus healthy participants; a systematic review and meta-analysisTime domain measure comparison between postural orthostatic tachycardia syndrome versus healthy participants. a illustrates three of twenty eligible studies that compared time domain measure outcome in terms of mean RR-intervals; b illustrates three of twenty eligible studies that compared time domain measure outcome in terms of mean rMSSDBack to article page